Characterization of glioma spheroid viability and metastatic potential following monophasic and biphasic pulsed electric fields.

Currently, the leading 3D cell culture models for characterizing and validating pulsed electric fields (PEFs) are spheroids and cell-laden hydrogels. We hypothesize that incorporating a glioblastoma multicellular tumor spheroid (MTS) onto a collagen hydrogel will leverage their strengths to form a more physiologically relevant model to study viability, proliferation, and migration. The MTS-hydrogel platform was subjected to PEFs varying in pulse width and electric field (EF) strength. Treated MTS were monitored and evaluated for viability and proliferation (Live/Dead imaging, XTT Cell Viability Assay), and migration (brightfield imaging) over 5 days post-treatment. In vitro experimentation was validated with a multi-layered spheroid finite element model, evaluating transmembrane potential (TMP), pore density, and pore formation across the spheroid layers. MTS exposed to longer pulse widths (5, 100 μs) and higher EFs (2000, 2500 V/cm) experienced a complete ablation. Smaller pulse widths and lower EFs produced partial ablations initially reducing the MTS, but unable to prevent the MTS from recuperating. Similarly shown with the computational model, a TMP was accomplished through the MTS, inducing electroporation; however, pore formation was dictated by the increase in pulse width and EF beyond the superficial layer. EFs of 2000 V/cm and above severely constrained the migration independent of pulse width.